Introducing the Stretch & Squish Theory of Evolution
Evolution is too slow if theorists rely on single point mutations, say two biologists from U. of Texas Southwestern Medical Center, who published their ideas in PNAS1 (see summary on EurekAlert). Instead, evolution proceeds by rapidly distorting, stretching and squishing what is already there, they claim.
They claim that even Darwin knew that evolution was fast: “In an observation that has evolved into the modern theory of punctuated equilibrium, Darwin inferred from the fossil record that evolution frequently occurs in rapid bursts.” In an effort to find a molecular basis for speeding up evolution to make rapid changes possible, they examined genetic sequences called tandem repeats from the blood of different breeds of dogs.
Most scientists agree that over very long periods of time, mutations in the genetic code are responsible for driving evolutionary changes in species. One widely accepted hypothesis is that random, so-called single-point mutations – a change from one letter to another among the billions of letters contained in the code – minutely but inexorably change an organism’s appearance.
UT Southwestern scientists, however, believe the single-point mutation process is much too slow and happens much too infrequently to account for the rapid rise of new species found in the fossil record, or for the rapid evolutionary changes occurring in species such as the domestic dog, whose various breeds have evolved relatively quickly from a not-too-distant common ancestor.
Mutations in tandem repeat sequences apparently occur 100,000 times as often as point mutations, and produce noticeable changes in appearance quickly, they claim. Dr. John Fondon explains:
“I was struck by the prevalence of very highly mutable tandem repeats in the coding regions of genes responsible for development,” he said. “That’s when it occurred to me that this may be an important mechanism whereby our genomes are able to create lots of useful variations in genes that are important for our development, our shape and structure, and our overall appearance. “Many of the shape difference that we see in evolution are not suddenly adding a wing or a leg. They are distortions, the stretching or squishing of a body part. Mutations in these repeat sequences are responsible for such incremental, quantitative changes.”
In the case of humans, mutations in neurons might have distorted, stretched and squished our brains: “Humans rapidly evolved big brains, which helped them survive as well,” suggested the other researcher, Dr. Harold Garner.
Update 12/22/2004: Elizabeth Pennisi in Science2 calls this the ”Ruff” Theory of Evolution. She notes that not all agree with the hypothesis that tandem repeats drive the evolution dogsled:
Sean Carroll from the University of Wisconsin, Madison, worries that Fondon and Garner overestimate the importance of tandem repeats in typical evolution, noting that dog owners have bypassed natural selection by breeding for physical characteristics without thought to how the resulting changes would impact a dog’s survival in the wild. Intensive breeding may have prompted the rampant changes in tandem repeats, more so than would occur under natural conditions. But David King, an evolutionary biologist at Southern Illinois University in Carbondale, argues that it doesn“t matter whether natural selection or artificial breeding is at work–the role of tandem repeats is now clearly important: “[Fondon and Garner] have shown that tandem repeats are effective for fine-tuning evolution.”
1John W. Fondon and Harold R. Garner, “Molecular origins of rapid and continuous morphological evolution,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0408118101, published online 12/13/2004.
2Elizabeth Pennisi, “A Ruff Theory of Evolution: Gene Stutters Drive Dog Shape,” Science, Vol 306, Issue 5705, 2172, 24 December 2004, [DOI: 10.1126/science.306.5705.2172].
This evolutionary food for thought is fit for a King. (Here, King; here, boy.) How do you squish an arm into a wing, or stretch a fin into a leg? This sounds like the silly putty theory of evolution. An intelligent kid can purposefully make things out of silly putty, but the putty by itself is silly and has no goal in mind. Put the silly putty into a random machine of moving parts and chaos results.
Other problems quickly evolve from this theory. What if the top of the dog’s snout gets stretched by a tandem repeat mutation, but the bottom jaw does not? The dog can’t eat. What if the mutated dog can eat, but cannot find a mate with the same mutation? And don’t these guys know that dog breeding is not evolution, but intelligent design? How can David King, an evolutionary biologist, appear so ignorant of the difference between natural and artificial selection? And how can he use evolution and fine-tuning in the same phrase?
For these and other reasons, this Silly Putty theory of evolution gets Stupid Evolution Quote of the Week. Fondon and Garner’s final sentence in the paper makes tandem repeats responsible for all the beauty and variety of living things:
How broadly this mode of evolutionary change is exploited in nature remains to be seen, but if the prevalence of repetitive elements within genes is any indicator, then mammals, insects, plants, and other genomes throughout the natural world may use this mechanism to achieve evolutionary agility.
“Evolutionary agility” – now there is an equivocation for the record books. How did a lizard learn to fly? By evolutionary agility. How did an ape learn to build spacecraft? By evolutionary agility. How did a dog learn to become a whale and dive deep into the ocean, navigating by sonar? By evolutionary agility. What an agile concept.
Papers like this diminish the prestige of the National Academy of Sciences. Peer review is supposed to prevent dumb ideas from getting published. If it were not for the desperation of the Darwin Party to keep sending new ideas up the flagpole to see if anyone salutes, they would have been forced to admit defeat long ago. This entry’s only value is in pointing out that the old neo-Darwinian theory of natural selection, acting on point mutations, is inadequate to account for the rapid change found in the fossil record. That is an admission that supports creation, not evolution.